مطالعۀ نقش همراهی مولکول بتاستلایت پیچیدگی برگ گوجه فرنگی در تشدید بیماری ناشی از ویروس پیچیدگی برگ کنجد در گیاه هندوانه

The association of betasatellite molecules with begomoviruses as well as two mastreviruses leads to induction of severe symptoms in various economical crops in different regions of the world. Previously, Sesame curly top virus (SeCTV, genus Turncurtovirus family Geminiviridae) and tomato leaf curl betasatellite (ToLCB) was detected in watermelon plants showing severe symptoms including leaf curling, brittle leaves and dwarfing collected from Jiroft farms (Kerman Province, southeastern Iran). In the current study, the role of betasatellite molecule in aggravating disease caused by the virus was studied using agroinoculation of watermelon plants with the virus and betasatellite constructs. Accordingly, a head-to-tail dimer of genomic clone of ToLCB was constructed using the pGreen0029 vector and resulted recombinant plasmid accompanied by the helper plasmid (pSoup) were transformed into Agrobacterium tumefaciens cells of strain C58. ToLCB construct and previously constructed partial dimer of SeCTV genome (sesame isolate) were used for pathogenesis studies in watermelon seedlings. Watermelon plants at the three to four-leaf stage seedlings were agroinoculated with A. tumefaciens cells containing SeCTV or SeCTV+ToLCB constructs and their reactions were compared with each other and with healthy watermelon plants. The infection of agroinoculated plants was checked by PCR assay using specific primer pair of SeCTV and ToLCB. Based on the results of this study, agroinoculation of watermelon seedlings with SeCTV+ToLCB constructs was led to induction of more severe symptoms including general yellowing, leaf curling and brittle leaves in compared to yellowing and dwarfing symptoms of plants agroinoculated with SeCTV construct alone. These results indicated that association of a betasatellite molecule with a turncurtovirus can intensify disease severity caused by the helper virus. It is the first report of the association of a betasatellite molecule with a turncurtovirus and aggravation of severe symptoms caused by the helper virus